The present invention relates, in general, to a device for measuring the temperature of a winding-carrying structural part of an electric motor, and to a method of determining the temperature in a winding area of an electric motor.
An electric motor of a type involved here generally includes a primary part and a secondary part which are disposed in opposite spaced-apart relationship to define an elongated air gap therebetween. The primary part is typically made of an iron body in the form of laminated electric sheets, and has slots for receiving current-carrying windings. Operation of the electric motor generates heat, in particular in the primary apart, which must be carried away to the outside to prevent in the primary part an unacceptable temperature rise that may damage the winding insulation or permanently destroy the primary part. An attempt to address this problem involves the provision of a thermocouple as thermal sensor in the area of the windings for monitoring the temperature in electric motors, in particular high-power motors. This approach suffers shortcomings because the thermocouple operates relatively sluggish as a consequence of the solid insulation and because the positioning of thermocouples with spot measurement cannot be adequately reproduced and results in measuring errors of ±10° C.
It would therefore be desirable and advantageous to provide an improved temperature measuring device which obviates prior art shortcomings and which is simple in structure while still being reliable in operation and yielding precise results.
It would also be desirable and advantageous to provide an improved method of determining the temperature in a winding area of an electric motor.